In subsea well operations, seals are often required in the annular space between tubular members, such as between a hanger and the wellhead housing surrounding the hanger from which the hanger is supported. Sometimes difficulty is encountered in that the members are not exactly concentric and this creates a differential in the radial space in which the seal is to be positioned. Obtaining a metal-to-metal type sealing engagement with such an eccentric annular space is very difficult and fraught with errors and troubles.
Seals which have been used have included the seal disclosed in U.S. Pat. No. 3,649,032 which includes a resilient member having a malleable metallic ring including axial undulations providing inner and outer annular crests which seal against the inner and outer sealing surfaces.
U.S. Pat. No. 4,641,708 discloses a subsea casing hanger having an annular seal that includes a main body with an inner upstanding rim and an outer upstanding rim having grooves on the inner surface of the inner rim and on the outer surface of the outer rim and a flexibility groove in the base immediately below the junction of the rims to the base and an annular wedging ring adapted to move between the two members to bring them into sealing engagement with the interior surface of the well housing and the exterior surface of the hanger. It is noted that a groove surface is provided in the housing and hanger surfaces, but it is positioned above the sealing portion on the inner and outer rims.
U.S. Pat. No. 3,913,670 discloses an annular seal to seal between elements in a subsurface wellhead which includes a resilient annular packing which is compressed axially to expand it radially inward and outward into sealing engagement with the inner and outer surfaces defining the annulus.
U.S. Pat. No. 4,550,782 discloses an annular seal for a wellhead which includes an annular ductile metal ring with inner and outer grooves connected by bores and an elastomeric material embedded in and extending from said grooves and bores. The exterior surface of the ring is cylindrical and the interior surface is tapered upwardly and inwardly.
U.S. Pat. No. 4,595,053 discloses an annular seal for use in sealing between subsea wellhead equipment which includes wickers or small parallel and circular grooves formed perpendicular to the axis of the bore. The seal is an annular ring which is cup-shaped in section and includes a wedge ring which is forced into the seal opening to wedge the sides of the seal ring into sealing engagement with the wickers.
U.S. Pat. No. 4,595,063 discloses another wellhead structure in which a pair of resilient seal rings are positioned on opposite sides of a metal ring and are actuated by axial compression with a ring having legs extending into individual engagement with each of the resilient seal rings.
While each of these devices of the prior art provide sealing between wellhead members none of them is capable of having metal-to-metal sealing engagement between such members when the members are not concentric.